I just dug the monster snowcave of all snowcaves a few weeks ago. depending on temp they can last all winter. and depending how deep in the snowpack you dig it. There are plenty of resources on how to construct one.
Key points
1. Dig the cave in a dome shape, it is the strongest
2.They usually only collapse late spring or while you are digging, don't have everyone in the cave digging at the same time
3. Dig the tunnel entrance's roof lower than the floor that you will sleep on, it creates a heat/wind trap
4.I think its easiest to start digging the tunnel with one person and the other person stand on top of the center of where you expect your main room to be, the person on top will dig straight down and carve out a cave while the other person digs the entrance to connect to it. It makes snow removal much easier. Once you are done digging straight down and doming it out, cover the hole in the roof with sticks and logs and then cut blocks of snow to put on top of the sticks, it will settle and refreeze to be rockhard within an hour, by the next few storms it will be bombproof.
5. Invest in a snowsaw they are soooo money.